<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    body {
      padding-top: 10px;
      /* background: yellow; */
    }
    .all_bg{
      width: 800px;
      height: 600px;
      margin: 0 auto;
      /* background: yellowgreen; */
    }
    #allcanvas{
      position: relative;
      width: 800px;
      height: 600px;
      margin: 0;
    }
    #canvas1{
      position: absolute;
      bottom: 0;
      left: 0;
      z-index: 1;
    }
    #canvas2{
      position: absolute;
      bottom: 0;
      left: 0;
      z-index: 0;
    }
  </style>
</head>
<body>
  <div class="all_bg">
    <div id="allcanvas">
      <canvas id="canvas1" width="800" height="600"></canvas>
      <canvas id="canvas2" width="800" height="600"></canvas>
    </div>
  </div>
  <script type="text/javascript" src="./js/main.js"></script>
  <script type="text/javascript" src="./js/commonFunctions.js"></script>
  <script type="text/javascript" src="./js/background.js"></script>
</body>
</html>